Maternal separation facilitates extinction of social fear in adult male mice.

Early life stress, such as child abuse or neglect, is a risk factor for the development of psychopathologies characterized by abnormal social and emotional behaviors. In rodents, long-lasting changes in stress coping and emotional behavior can be induced by separating pups from their mother. We used maternal separation (MS; 3h daily on postnatal days 1-14) to test whether early life stress alters acquisition and extinction of social fear in adult male mice as studied in a specific model of social fear, i.e., in the social fear conditioning paradigm. We show that MS facilitated extinction of social fear without altering acquisition or expression of social fear. This facilitatory effect of MS on social fear extinction was not due to improved social learning and memory abilities or to increased social interest, as MS rather impaired social memory in the social discrimination test and did not alter social preference in the social preference-avoidance test. In contrast, MS did not alter acquisition and extinction of non-social, cued fear, or non-social memory as assessed in the object discrimination test and non-social anxiety as assessed in the elevated plus-maze. These results suggest that a social stress like MS in early life may improve coping with and recovery from a traumatic social experience in adulthood in mice.